DAYTON, Ohio (AP) - With Aaron Craft's last-second shot, No. 2 Ohio State remained the lone high seed left in the NCAA tournament's most-busted bracket.

Craft made a 3-pointer with a half-second left, and Ohio State escaped Dayton - a place of Buckeye heartaches - with a 78-75 victory over Iowa State on Sunday.

Ohio State (28-7) needed Craft's only 3-pointer of the game - an arching shot over 6-foot-7 defender Georges Niang from the top of the key - to avoid yet another upset in the oh-so-wild West Regional. Four of the top five seeds fell fast and hard in the first weekend.

Craft left the Buckeyes in position to fritter away a late lead, then saved them in the final second.

"I tried to stay as poised as possible," Craft said. "Missed a lot of shots I normally make, layups and free throws. Got a mismatch, took the ball, and it went in."

Ohio State's 10th straight win sent the Buckeyes into the round of 16 for the fourth straight year, a school record. They'll play sixth-seeded Arizona on Thursday in Los Angeles.

Tenth-seeded Iowa State (23-12) overcame a late 13-point deficit by hitting 3s - the Cyclones' specialty - but wound up beaten by Craft's lone basket from behind the arc. The plucky point guard helped Iowa State take it to the closing seconds by missing the front end of a pair of one-and-one chances.

He also missed a jumper with 30 seconds left, but the Cyclones knocked the ball out of bounds going for the rebound. The Buckeyes spread the floor for the final play, which ended with Craft flinging it up.

Deshaun Thomas led Ohio State with 22 points, and Craft had 18. LaQuinton Ross scored 10 straight for the Buckeyes as they built that second-half lead.

Korie Lucious led Iowa State with 19 points. He didn't come close on a final heave after Craft's winner.

Iowa State coach Fred Hoiberg was unable to make an opening comment during the postgame news conference, the pain of the defeat etched all over his face.

"We played our hearts out," Will Clyburn said. "It was a tough game and he made a tough shot. He made a great play."

The Buckeyes escaped Dayton - the scene of a couple of a couple recent NCAA tournament disappointments - as the lone high seed left in the West.

No. 3 New Mexico, No. 4 Kansas State and No. 5 Wisconsin were knocked out right away, losing their openers. No. 1 Gonzaga joined them Saturday night, shocked by ninth-seeded Wichita State 76-76.

The Buckeyes had opened the tournament in Dayton twice previously under coach Thad Matta. Twice, his Buckeyes failed to advance even though the thousands of fans provide a home-court feeling.

It was fitting that this one was decided by a 3.

The Cyclones lead the nation in 3-pointers, with nearly 44 percent of their attempts coming from behind the arc. Defense has been Ohio State's foundation during its late winning streak, which included the Big Ten tournament title.

With Craft anchoring Ohio State's perimeter defense, the Cyclones had trouble getting open shots and missed eight of their first 12 from behind the arc.

The Buckeyes' offense also was ragged at the outset. Even the Buckeyes' best stretch in the first half came with a downside - Shannon Scott had a steal and layup, but bounced the ball at the defender after his score, drawing a technical foul.

Iowa State guard Chris Babb got treatment on his left leg in the final minute of the half and went to the locker room early. Babb, who is second on the team in 3s, didn't come out for second-half warmups and sat on the floor at the end of the bench in his sweats.

The Buckeyes pushed the lead to six points at the start of the second half, but the Cyclones stayed close by giving themselves second chances. Melvin Ejim's putback cut it to 52-51, and he and Craft bumped into each other and traded words heading into a timeout with 11:43 left.

Neither side was backing down.

Coming out of the timeout, the Buckeyes put together their best run of the game. Ross hit a pair of 3s, a layup off a steal and two free throws for a 65-53 lead with 8:18 to go.

The Cyclones turned to the 3 - both versions - to pull even. Lucious' three-point play tied it 69-all with 3:53 left, completing a 13-0 run. Craft missed the front end of a pair of one-and-one chances during that spurt.